The present invention relates generally to a support stand or tripod for an item of equipment that requires a stable and steady support, for example optical equipment such as a photographic, film or video camera or the like.
One known form of such a support stand comprises a head portion to which the device to be supported on the stand is mounted, and support legs which extend downwardly away from the head portion of the support stand. The support legs are formed by tube portions in telescopic relationship, that is to say, each support leg comprises at least first and second tube portions of which one is telescopically movably disposed within the other. The telescopically related tube portions of each leg can be readily locked in any position relative to each other, by means of a suitable fixing device. The fixing device may be of such a nature that it comprises a clamping cone member which is operable from outside the leg of the support stand, and a pressure element which co-operates with the cone member and which can be expanded thereby to brace against the outside telescopic tube portion. However, when the fixing device is not in the leg-locking position, the tube portions tend to collapse downwardly due to the force of gravity acting thereon. As a result of that, an item of equipment which is to be set at a given level, for example a camera or the like, by means of the support stand, must be firmly held at the required height, while the fixing device is in the unlocked condition so that the telescopic tube portions can move easily with respect to each other, so that the fixing device can then be actuated to lock the tube portions relative to each other, thereby to fix the respective legs at the appropriate lengths. It will be appreciated that it is often difficult to hold the camera or other item of equipment at the appropriate height, while the legs are being allowed to take up the appropriate positions in respect of length, and that means that it is frequently very difficult to set the item of equipment precisely at the desired position.
Furthermore, in the case of support stands or tripods in which the fixing device comprises a pressure element operable by means of a clamping cone member which can be actuated from outside the telescopic tube portions of the respective legs, thereby to clamp against the inside of the telescopic tube portion, the fixing device suffers from the disadvantage that the region in which the design of the stand provides for guidance for the telescopic tube portions in the axial direction is very short when the tube portions are in the condition of maximum extension, that is to say, when the legs are set to give their maximum lengths. That means that, most particularly when the tube portions are at their positions of maximum extension, the two tube portions of each leg may be relatively easily inclined relative to each other and thereby buckled, even when the tube portions are in the fixed and locked condition by virtue of the fixing device having been actuated. Quite apart from the danger of the legs being damaged in that way, the fact that the telescopically related tube portions of each leg can become inclined relative to each other due to the short length of the guide means for guiding the tube portions relative to each other means that the stability of the stand is often inadequate.